Iíve been investigating several things lately. System Tuner, like other tools, always show a constant CPU speed, never changing. It looks like the CPU speed is fixed. Thatís strange! Tools like System Tuner get their information from sysfs, so I looked at where and how those items are filled from within the kernel, or better, where they should be filled.

I added some extra logging to see what (not) happened and got the part fixed that reported the cpu speed back to userspace. While browsing through the logging I saw a different error early in the boot process saying something like ďvdd_core canít get regulator in clk_enable_dvfsĒ. I wondered what that meant. Investigating the dvfs (Dynamic Voltage & Frequency Scaling) mechanism I found that parts are missing and other parts are not working. The good thing is that the source code is provided, the bad thing is that, although itís easy adding the missing parts, it still doesnít work. The error messages disappeared, but the device now has trouble reading back the current voltage value. I ended up disabling dvfs completely for the time being. By doing so, looking at the code, this also removes some overhead and (hopefully) increases speed and stability.

The RK30 platform code has a build-in ďintelligenceĒ in regards to cpufreq governors, putting hardcoded limits on frequency scaling in place. I donít like hardcoded limits, so I removed them. I added some new governors, being SmartassV2, InteractiveX and SavagedZen and made SmartassV2 the default one. I also added IO schedulers VR and SIO.

From one thing came the other. I started tweaking the frequency table, and added overclock frequencies for 1.7GHz and 1.8GHz. Testing these frequencies with the new governors it looks like 1.7GHz is the highest stable frequency. I normally use the AnTuTu benchmark for testing, but on the MK808 AnTuTu in the current version (v3.1.2) always crashes on executing the 3D benchmark. Testing with 1.8GHz results in a complete device hang-up at some point. It seems to be a heat problem, because after a while it doesnít even boot anymore, and I actually needed to cool the device down to get it working again. So beware if you want to give this a try yourself!

Thatís it for now. Iím still working on the touchscreen driver, and my todo list is getting longer and longer. If I didnít respond to your comments or mails... sorry about that! I added most requests already to the todo list for further investigation.

Thereís a MK808B underway from Spain (thanks Alejandro!) and as you can see on the top-right of this blog, szTomato as one of the manufacturers of the MK808 is sponsoring me as well. More on that later.

Kernel download

The kernel can be downloaded here. Flash it in the usual way. The zip file contains only the 720p for DVI kernel. Sorry about that, but Iím short in time. Needless to say maybe, but be careful when using the CPU overclocking feature. It can damage your device!!

I've been busy with lots of kernel changes. Too many to mention them all seperately here. I merged a lot of code from the 3.0.50 linux kernel into our 3.0.8+ code base. One big change worth mentioning is that I added touchscreen monitor support from the mainline 3.8 linux kernel. Since I don't own a touchscreen monitor myself I ask all of you proud owners of such a device to test this kernel and see if it works. Please don't forget to report your findings here of course.

Some of you reported that you still have 'No signal/Black screen' problems. I had trouble myself using the MK808 on my TV (HDMI) and my monitor (DVI). Each time one of the two devices ended up having a 'No signal/Black screen'. In the comments of my previous post you also asked for a 720p fixed resolution instead of 1080p. That's why this release has four different versions of the kernel. One for each output connecion, being DVI and HDMI and for each output a 720p and a 1080p fixed resolution. All four kernels have their own distinct default setup, being:

HDMI output with 720p fixed resolution

HDMI output with 1080p fixed resolution

DVI output with 720p fixed resolution

DVI output with 1080p fixed resolution

These settings are activated on bootup of the kernel, and are fixed as long as the 'autoconfig' feature is disabled. This feature is disabled on default, and can be re-enabled as described in my previous post. As long as 'autoconfig' is disabled, the fixed output and resolution remain in tact, whatever you do. Even changing the resolution from Android won't work! If you re-enable 'autoconfig' the output as well as the resolution can be changed to your liking again.

Kernel download

I realize I haven't uploaded my github account lately. With a shortage of spare time I tend to choose doing more fun stuff than uploading changes. I promise I'll spent some time on cleaning up the code a bit and upload a new snapshot of my code base.

In the meantime I hope you all have fun with this release. Please give it a try and sent me feedback of your findings. Enjoy!

I've had several reports in regards to my 'Black screen/No signal' kernel fix, ranging from "Perfect, it finally works!" to "Still doesn't work" or "Sound doesn't work". I thought about a better solution, so I made another few adjustments to the HDMI driver.

In short, the default HDMI settings in my latest kernel are: HDMI enabled for image AND sound (took a while to get that fixed!), Autoconfig disabled, predefined resolution 1920x1080p at 60Hz. Hopefully these settings work for most of you. My guess is they will.

To give you more control over the HDMI driver you need to get access to the device. Use adb shell to do this from your PC. This is probably the only option you have when you have the 'No signal' problem (duh!). Then you need to find out what the best configuration for your display is. This is done using sysfs. Try experimenting with different settings. After that you can create an init.d boot script to make the settings permanent. On bootup of the device, the init.d script will configure the driver according to your preferred settings.

1. HDMI output

Use this setting to enable or disable HDMI output. Reason for disabling could be that you're using your device headless and you want to save as much power as possible. On default HDMI output is enabled.Enable (default):

echo "1">/sys/devices/virtual/display/display0.HDMI/enable

Disable:

echo "0">/sys/devices/virtual/display/display0.HDMI/enable

2. Automatic configuration

The effect of enabling automatic configuration is twofold. First the "Hotplug" feature reacts on connecting and deconnecting a display and second the HDMI driver tries to read configuration information from your display using EDID and configure HDMI image and sound in the highest possible mode. This is the way the original stock kernel worked. In this kernel I disabled automatic configuration on default, but you can re-enable it if you want.Enable:

echo "1">/sys/devices/virtual/display/display0.HDMI/autoconfig

Disable (default):

echo "0">/sys/devices/virtual/display/display0.HDMI/autoconfig

By disabling automatic configuration the "Hotplug" feature is disabled as well. The driver then acts as if a HDMI display is always connected. Sound output is set to HDMI as well. Apart from that, the driver no longer tries to read the configuration from your display using EDID. Only a predefined set of display modes can be used. The default resolution is set to 1920x1080p, 60Hz. Be aware that the stock Android image resets the resolution to a lower 1280x720p, at least on the one I use. Currently following predefined resolutions are being supported when automatic configuration is disabled.

2880x480i-60

2880x480p-60

2880x480p-60

2880x480p-50

2880x480p-50

1920x1080p-60

1920x1080p-50

1920x1080p-50

1440x480p-60

1440x240i-50

1440x240p-60

1280x720p-60

1280x720p-50

720x576p-50

720x480p-60

720x480p-50

To change the resolution use the exact format from the list above. For example, to set 1280x720p-60 use:

echo "1280x720p-60">/sys/devices/virtual/display/display0.HDMI/mode

Kernel download

The kernel can be downloaded here. Flash it in the usual way. Although a lot of the kernel is updated to version 3.0.50 already, I still kept the 3.0.8+ version number intact, so the stock Android image can still load it's kernel modules and keeps working as normal.

Please report any of your findings here! I'm very curious to know whether or not this once and for all solves these annoying 'No signal' display problems.

From day one I had difficulties working with the MK808. None of my LCD displays worked with the device. All gave a black screen, no image at all. The only exception was my Samsung TV set. Not so handy when developing stuff for the MK808, tweaking the kernel, changing the Android OS or even create new distributions like Ubuntu or XBMC.

So in the beginning I used 'adb' a lot, and walked over to the TV set in the living room like a million times, asking my wife again and again if it's okay to "borrow" the TV for just a minute and test my latest change(s)

Now, having the serial console feature, debugging has become so much easier. The console is available early in the kernel boot process, and the device is accessible from my PC. A lot of mistakes you make when customizing the kernel show up on the console, which is very helpful.

This is how I found out that, although no image showed up on my LCD monitor, detaching the monitor was detected by the HDMI driver. This made me think. Could it be a flaw in the HDMI driver after all? All the "solutions" I read about online were related to adding (powered!) splitters, (powered!) repeaters or other converters/adapters to the MK808. In my opinion, one of the nice things of a device like this is that is has an ARM CPU which uses very little power. The succes of having such device 100% working for me would be having a small extremely powerful, "always on" and very low powered device. That's why adding all kinds of additional powered hardware is a real show stopper to me.

Delving into the HDMI device driver code, I looked at the "hotplug" feature. This feature signals any changes on the HDMI port, connecting or disconnecting a display for instance. I changed the code by telling the driver that a display is always connected, in effect disabling the hotplug feature. I also set the resolution fixed to 1280x720 60Hz (1080p720p). This works! Booting the customized kernel now finally shows the Android home screen on all my displays.

For all of you having the same black screen/no image problem, please try flashing the kernel, and let me know if this fixes the problem for you as well. Included in this 3.0.8+ kernel are a lot of additional patches and changes, cherry picked from the 3.0.50 kernel release. I'll continue to upgrade the kernel to a higher level.

[Update] 2013-01-20 Sound issue fixed.

As some of you know, I've been working on the MK808 TV Stick/Mini PC for some time now. The MK808 is based on the dual-core Rockchip RK3066. A quite powerful SOC, capable of doing the average stuff most of us do every day with a desktop PC. Unfortunately, Rockchip is one of those manufacturers that don't comply to any open source license agreement. Simply put, the rule of thumb is that when you use open source you have to give all the modifications you make when selling products based on GPL back to the community. Well, Rockchip doesn't comply to these rules. Worse, they make their own license rules, saying that they are the sole owner of all software, including all GPL parts. That's why most hardware manufacturers say they aren't allowed to give any of the sources. Too bad they don't seem to understand the value of working together on making things better. Oh well, enough of this, I think I made my point clear. It's just so frustrating!

Luckily there are a few hardware manufacturers that understand the value of GPL. Or it may be that they don't understand the chinese license agreement from Rockchip. Or it may just be that they understand the underlying GPL agreement, unlike Rockchip. It may be a coincident also, but all the manufacturers providing some of the Rockchip adaptations of the Linux kernel seem to be based outside the people's republic of China. Anyway, it doesn't matter how, what matters is that we finally have a few snapshots of the Rockchip linux kernel adaptations after all.

Unfortunately, from all current available snapshots a lot of the essential code is missing. This makes it a difficult process to get all the hardware components working. Some code parts are delivered in binary object files only, which prevents you from making changes without going through the time consuming process of disassembling and reverse engineering.

I tried to upgrade the MK808 kernel to a higher version of the linux kernel a while ago. Reason for this is to apply common (mainline) patches and enhancements and to add some new features as well. I failed miserably. The device didn't boot, and I came to the point that I had no ways to find out what error(s) I had made. The kernel died early in the boot process. This is a common problem in kernel development. One way to find out what goes on during the boot process is the use of a serial console. I saw this great blogpost a while back about the UG802. It's a similar device using the same Rockchip RK3066 CPU. Although the PCB layout is completely different of course, I imagined that PCB designers would always create ways to debug low-level problems like I had. This is easy to say with the little knowledge of hardware that I have I looked at detailed images of the MK808 PCB and saw some connector pins that could indicate the possible use of a serial console.

This is where my brother comes in. He has a strong hardware background, always messing around with Arduino's and the like. I asked him if it was as easy as I thought it would be. The short answer was... No, it's not "just" soldering three wires onto the MK808 mainboard and connect them to the serial port of a PC. You have to know, I'm a software guy, so in terms of background my brother and I come from two completely different worlds. He tried to explain the importance of voltage conversion for instance. The PC using 12V whereas the MK808 only uses 3.3V. Talking about the risk of blowing up the device if not being careful. Or why it doesn't make sense to "just" replace the Wifi antenna with a bigger model. I have to say, most of this is all way beyond the scope of my understanding!

Anyway, to cut an already long story a little shorter, my brother came visiting me saturday afternoon and we took the plunge and started to mod the MK808. What I suspected was that the three pins just outside the CPU area were meant for debug purposes. Like on the UG802. This was a long shot of course, but that was just my simplistic way of thinking

With my newly bought soldering iron, multimeter, connectors and a FTDI serial to USB breakout board we started checking out these three pins. We were in luck. The first pin we checked was the receive (RX) pin for a serial console. Tadaaaa! The MK808 booted, and we saw console output on the PC. Wow! After that it was easy to guess the transmit (TX) pin, having only two more pins left, leading to a complete working serial console in no time. How cool is that!

Most time went into putting everything back together. The heatsink had to be put back in place and we needed to get the wires connected to the FTDI board outside the case. We made a connector on top of the device so the FTDI board can now be easily connected and removed if needed. Look for yourself, I think it looks slick, and more importantly, it works perfectly well!

I couldn't have done this without the help of my brother, so all credits go to him. Thanks bro, a job very well done!

I've added "zRam" to the kernel. This feature was previously known as "compcache". It increases performance by avoiding paging on disk and instead uses a compressed block device in RAM in which paging takes place until it is necessary to use external (disk) swap space.

I'm still testing it, but it seems to have a positive effect in terms of performance.

You have to enable it manually for now. Use a terminal emulator or use "adb shell" to do this more comfortably from your desktop.

I got in touch with "genokolar" today, since he managed to get the camera flash fixed on the U8818. He was kind enough to send me his patches, so all credits go to him for this release. I also added some more overclock frequencies, up to 1.5GHz, but they result in reboots only. At least for now...

I've created a repository on github, so please feel free to fiddle around with the sources yourself.

A quick update of the G300/U8815 kernel. This update fixes bluetooth. Tested this afternoon, and it works perfectly now. Tomorrow I will look into the camera flash that's not working. I will also start stripping the kernel a bit, removing unnecessary parts that only take up precious memory. Maybe I try to add some extra overclocking as well, although I don't think the current "lagging" most of us see every now and then is fixed by only increasing the CPU frequency.

In the top 10 excuses for not blogging for so long my excuse would be... well, I don't have an excuse, I'm still here and that's what counts

I've build a kernel for my Huawei G300/U8815 smartphone yesterday. Based on the Huawei v3.0.8 kernel code, I've added overclocking, governers and I/O schedulers and added some minor tweaks here and there. Not a lot of other features yet, but I'm quite surprised with the results so far in battery life and performance. So see for yourself. Tested with stock Huawei B927 ROM, up to 1.3GHz.

Tested for performance with max 1.306GHz and min 480MHz frequency, governor "Performance" and I/O Scheduler "VR" I get a AnTuTu score of 3542. This is with lots of applications installed and active. Not bad at all I think

Tested for battery life with max 1GHz and min 122MHz frequency, governor "SmartassV2" and I/O Scheduler "VR" for 11 hours. Battery dropped 0%(?!) during that time. While not sure if that's really correct and representative I started using the browser intensively, made a 5min telephone call and used whatsapp. Battery dropped from 75% to 68% during that time. Needs more testing I guess, but please post your results here!

Use something like "No-frills CPU control" from the Market to quickly set the CPU frequencies, Governor and I/O Scheduler to use. Try different options to find out which combination works out best for your specific situation(s).

I packaged the kernel as an "update.zip" so it can be easily flashed from CWM. It only updates the kernel, no need to clear caches or wipe data or anything. Just make sure to have a backup in case you want to go back to the stock kernel.

Needless to say maybe, but I'll do it anyway... Be careful with overclocking your device. Overclocking will cause a CPU to have a shorter life expectancy. Apart from that, I take no responsibility whatsoever if you fry your CPU

Last but not least a shameless plug... there is this nice "Donate" button on the left side of this page. Feel free to use it if you like what you see.

Having my GuruPlug all set up I started building Ubuntu Lucid Lynx (v10.04) some time ago. From scratch, compiled natively, that is. It took me quite some time to get myself acquinted with (re)packaging first, but now I kind of seem to manage my way through it most of the time.

Ubuntu Jaunty (v9.04) was the last version that supports armv5te CPUs. The current versions only runs on the newer ARM processors (armv7+). So that meant I had to re-target all armv7 specific packages to make them work on the (older) armv5te CPUs again. Since this is the only way to get the newer Ubuntu versions going on our beloved Zaurus, it had to be done!

What a work! It probably can be done much quicker, but here's what I did. I took a debootstrap of the ARM (armv7+) version of the official Ubuntu Lucid version to begin with, and started rebuilding all packages one by one, re-targetting them for the armv5te CPUs. Some of the packages need special attention, and others can "just" be recompiled. I have to say, the GuruPlug is really a marvellous piece of hardware, and just perfect for doing this kind of stuff. It's just great not having to concentrate on all these cross-compilation problems you have to deal with when building ARM packages on the i586 platform. I can assure you, the GuruPlug saved me quite some headache!

Before you're going to ask me where all the fun stuff can be downloaded, this post is first of all meant as a status update of the project. Currently I only have the minimal Ubuntu distribution working. All compiled from the original Ubuntu sources, with just minimal changes to some of the packages.

So, no, the complete repository isn't available yet. But I just wanted you all to know that the good news is that it is still possible to get the latest and greatest version of Ubuntu working on our Zaurus. Woohoo!